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川北地区下三叠统飞仙关组沉积主要受开江 梁平海槽控制 ,短期存在的海槽在其两侧形成了较为对称的类似于威尔逊相模式的碳酸盐岩沉积体系。通过详细的钻井、露头等岩石学资料的研究 ,认为飞仙关组主要发育蒸发台地、局限台地、开阔台地、台地边缘滩、斜坡和盆地相共六类沉积相。其盆地相较深海盆地相浅 ,主要发育深色泥灰岩和灰质泥岩 ;斜坡沉积特征明显 ,见浊流、碎屑流沉积 ,但陆棚相不发育 ,可能是海槽深度小、面积小引起的 ;随着海槽的关闭 ,海水变浅 ,海槽内部的沉积由盆地相向斜坡、台地边缘滩、开阔台地、局限台地、蒸发台地相演化特征明显 ;到飞四段顶部 ,整个川北地区均一化为局限台地相或蒸发台地相沉积。由于海槽存在时间短 ,沉积相在平面上和纵向上的演化过程十分清晰。随着海槽的关闭 ,海水向广海方向退却 ,台缘鲕滩也向海槽边界 ,即向广海方向发生了迁移 ,而且其发育层位逐渐变高。
The sedimentation of the Feixianguan Formation in the Lower Triassic in the northern Sichuan area was mainly controlled by the Kaiping Liangping Trough, and the short-term trough formed symmetrical carbonate sedimentary systems similar to the Wilson’s facies on both sides. Through detailed study of petrology data such as drilling and outcroping, it is considered that Feixianguan Formation mainly consists of six types of sedimentary facies such as evaporized platform, confined platform, open platform, marginal margin of platform, ramp and basin. The sedimentary facies of the basin is darker than that of the deep-seated basins. The sediments of deep slope are mainly composed of dark marl and gray mudstone. The sediments of the slope show obvious turbidity and debris flow deposition, but the shelf facies are not developed. The depth of the trough may be small and the area is small ; With the closure of the trough, sea water becomes shallower, and the sedimentation in the trough is characterized by the opposite slope of the basin, the margin beach of the platform, the open platform, the limited platform and the evaporation platform. The top of the fourth section of the flyover, Uniformized as a localized platform or evaporation platform deposition. Because of the short existence of troughs, the evolution of sedimentary facies in the plane and in the longitudinal direction is very clear. With the closure of the trough, seawater retreated to Guanghai, and the marginal oolitic beach migrated to the trough boundary, that is, toward Guanghai, and its developmental level gradually became higher.